title: Bicarbonate reabsorption in the papillary collecting duct: effect of acetazolamide.
abstract: The present study was designed to characterize bicarbonate (total CO2) reabsorption in the papillary collecting duct of the kidney of the Munich-Wistar rat when total CO2 delivery to this segment was increased by the systemic infusion of a bicarbonate-rich solution. Additional studies examined the effect of the systemic administration of acetazolamide, a carbonic anhydrase inhibitor, on total CO2 reabsorption. Employing free-flow micropuncture techniques, tubular fluid samples were obtained from the base and tip of the exposed papilla and subsequently analyzed for total CO2 and inulin. Total CO2 reabsorption increased in a linear fashion, approximating 34% of that delivered to the base, as total CO2 delivery increased from 3 to 20% of the filtered load. When examined at comparable absolute rates of total CO2 delivery (mumol/min) to the papillary collecting duct, acetazolamide administration resulted in marked inhibition of total CO2 reabsorption. The results of these studies suggest that the papillary collecting duct of the rat kidney possesses a significant capacity for reabsorption of total CO2 and that this reabsorption is diminished by the administration of acetazolamide.
mesh_terms: D000086:Acetazolamide / Q000494:pharmacology*; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D002245:Carbon Dioxide / Q000378:metabolism; D005260:Female; D007328:Insulin / Q000378:metabolism; D007668:Kidney / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D001639:Bicarbonates; D007328:Insulin; D002245:Carbon Dioxide; D000086:Acetazolamide